$$\text { Let } f ( n ) = 3 n ^ { 2 } + 8 n + 7 \text {. Show that } f ( n ) \text { is } O \left( n ^ { 2 } \right)$$

Essay

$$\text { Let } f ( n ) = 3 n ^ { 2 } + 8 n + 7 \text {. Show that } f ( n ) \text { is } O \left( n ^ { 2 } \right)$$ Be sure to specify the values of the witnesses C and k.